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ID Date Author Type Categoryup Subject
  9209   Sun Oct 6 22:52:09 2013 Jenne, RanaUpdateIOOinput beam to PMC aligned again

pmcr.pngafter

I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?

  9210   Sun Oct 6 23:43:07 2013 ranaUpdateIOOWFS debugging

Quote:

Tried a bunch of stuff, but eventually just turned off the TRANS_QPD loops and loops are stable. Needs more debugging.

  1. Modified the on/off scripts so that the Integrators are no longer toggled. No reason to turn them off since we are clearing the filter bank histories.
  2. With QPD feedback OFF, I have lowered the overall gain by 15x so that its just drift control.
  3. Deleted unused / bad filters from the main filter banks.
  4. Gautam is going to debug the QPD with a red laser pointer and then elog.
  5. Jamie is checking out the MC Coil dewhitening logic to see if that's in a funny state.

 Back around June 18, Jamie was debugging some Guardian code here to replace our MC autolocker. Afterwards our MC WFS stopped working. We never figured out what went wrong, but at the time we turned off the feedback from the MC trans QPD and it stabilized the response at DC.

Today, I noticed that the trans QPD feedback is on.  Did anyone do this on purpose?

Its problem causing behavior is slow, but you can catch it if you wait. With the nominal WFS gain of 0.4 the control signal ramps up monotonically at a rate of ~100 counts/minute. Depending upon the static alignment of the MC, this could let it take 10 minutes or a few hours before it rails the MC SUS actuators and breaks the lock. Very sneaky. Don't turn this loop back on without making sure its working and not breaking. I would trend it for you, but the SLOW channels associated with the TRANS QPD servo are not trended --- does anyone know how to get them in the channel list?

  9238   Mon Oct 14 17:51:40 2013 JenneUpdateIOOinput beam to PMC drifted again

Quote:

I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?

 The PMC refl is bad in pitch today, and the transmission is only 0.76, rather than our usual 0.83ish.

I did a quick, rough tweak-up of the alignment, and now we're at 0.825 in transmission.

  9256   Mon Oct 21 13:15:52 2013 KojiUpdateIOOPMC aligned

PMC aligned. Trans 0.78 -> 0.83

  9296   Sat Oct 26 21:46:33 2013 RANAUpdateIOOMode Cleaner Tune-UP

 The MC had been unlocked for the last 4 hours and was crying out to me so I gave it some attention. Its happier now.

From the trend (AtM #1), I saw that the MC2 suspension has moved by ~10 microradians. Since the MC cavity divergence angle is lambda/(pi*w0) ~ 200 microradians, this isn't so much, but enough to cause it to lock on bad modes sometimes. Attackmint too shows that there's not much in monotonic drift over the last 40 nights.

I moved back MC2 to its old alignment with these commands:

ezcaservo -r C1:SUS-MC2_SUSPIT_INMON -s -1017 -g 0.0009 C1:SUS-MC2_PIT_COMM -t 300

ezcaservo -r C1:SUS-MC2_SUSYAW_INMON -s 490 -g 0.0009 C1:SUS-MC2_YAW_COMM -t 332

Then I went out to the table and aligned the beam into MC using the last two steering mirrors good enough so that the WFS coming on doesn't make the visibility any better. In this nominal state, I unlocked the MC and then aligned the reflected beam onto the center of the LSC PD as well as the WFS. The beam on the first WFS is a little small - next time someone wants to improve our Gouy phase telescope, we might try to make it bigger there. On the LSC PD, the beam was off-center by a few hundred microns.

Attachment 1: MCtrend.pdf
MCtrend.pdf
Attachment 2: MC40days.png
MC40days.png
  9303   Mon Oct 28 14:12:48 2013 manasaUpdateIOOMode Cleaner relocked

Quote:

 The MC had been unlocked for the last 4 hours and was crying out to me so I gave it some attention. Its happier now.

From the trend (AtM #1), I saw that the MC2 suspension has moved by ~10 microradians. Since the MC cavity divergence angle is lambda/(pi*w0) ~ 200 microradians, this isn't so much, but enough to cause it to lock on bad modes sometimes. Attackmint too shows that there's not much in monotonic drift over the last 40 nights.

I moved back MC2 to its old alignment with these commands:

ezcaservo -r C1:SUS-MC2_SUSPIT_INMON -s -1017 -g 0.0009 C1:SUS-MC2_PIT_COMM -t 300

ezcaservo -r C1:SUS-MC2_SUSYAW_INMON -s 490 -g 0.0009 C1:SUS-MC2_YAW_COMM -t 332

Then I went out to the table and aligned the beam into MC using the last two steering mirrors good enough so that the WFS coming on doesn't make the visibility any better. In this nominal state, I unlocked the MC and then aligned the reflected beam onto the center of the LSC PD as well as the WFS. The beam on the first WFS is a little small - next time someone wants to improve our Gouy phase telescope, we might try to make it bigger there. On the LSC PD, the beam was off-center by a few hundred microns.

Masayuki was running LAN cables near the MC2 chamber. This caused the MC2 suspension to move and unlocked the MC. I looked at the long term (2 days) and short term (2 hours) trend of the MC suspensions. I restored the old alignment as described above using ezcaservo.

C1:SUS-MC2_SUSPIT_INMON was restored to 1020 and C1:SUS-MC2_SUSYAW_INMON was restored to 490.

Attachment: Dataviewer trend (2 hours)

Attachment 1: Screenshot-Untitled_Window-3.png
Screenshot-Untitled_Window-3.png
  9306   Mon Oct 28 21:33:55 2013 RANAUpdateIOOMode Cleaner Tune-UP

 

8 day minute trend of some of the IMC alignment signals.

That step ~2 days ago in the WFS2 yaw control signal shows that I didn't do such a good job on yaw.

Nic is going to come over some time and give us a new Gouy telescope that let's us have bigger beams on the WFS. At LLO, Hartmut demonstrated recently how bigger beams can reduce offsets somehow...mechanism TBD.

Also, we must angle the WFS and figure out how to dump the reflections at the same time that we rework the table for the telescope.

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 

Attachment 1: Untitled.png
Untitled.png
  9315   Wed Oct 30 01:53:52 2013 JenneUpdateIOOMode Cleaner relocked

The MC (mostly MC2) decided a few minutes ago to move, so I put the SUSPIT and SUSYAW numbers back where they were, and the tweaked up the alignment from there to get a low MC REFL DC number.  Now the MC is staying locked again, after 20 minutes of not.

  9320   Wed Oct 30 16:46:17 2013 manasaUpdateIOOMC aligned

MC has not been very happy since last night. 

What I did to fix this:

1. Disabled autolocker and WFS and aligned the MC to bring MC REFL down to <0.50

2. When I re-enabled autolocker, MC was losing lock everytime WFS turned ON.

3. I relocked MC, measured the spot positions and moved MC spot positions by running /opt/rtcds/caltech/c1/scripts/ASS/MC/mcassMCdecenter 
and 
/opt/rtcds/caltech/c1/scripts/MC/moveMC2/

4. I reset the WFS offsets by running /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets

5. MC is locked and looks happy right now with REFL DCMON at ~0.5

 

  9322   Thu Oct 31 15:34:28 2013 manasaUpdateIOOMC not happy since yesterday

Quote:

 

8 day minute trend of some of the IMC alignment signals.

That step ~2 days ago in the WFS2 yaw control signal shows that I didn't do such a good job on yaw.

Nic is going to come over some time and give us a new Gouy telescope that let's us have bigger beams on the WFS. At LLO, Hartmut demonstrated recently how bigger beams can reduce offsets somehow...mechanism TBD.

Also, we must angle the WFS and figure out how to dump the reflections at the same time that we rework the table for the telescope.

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 

The MC has not been able to hold lock for over a couple of hours since yesterday. I aligned the MC yesterday (elog 9320) and it lost lock in a couple of hours. I realigned the MC again around noon today only to see it drifting and lose lock again.

I have attached the MC trend for the 2 hours when the MC drifted slowly from its happy to sad state.

 

 

Attachment 1: MC_drift.png
MC_drift.png
  9323   Thu Oct 31 20:05:48 2013 RANAUpdateIOOMode Cleaner Tune-UP

Quote:

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 I couldn't find any dumps near the WFS. Koji looked. I looked twice. Maybe they are spooky and absorbing all of the light?

The MC alignment was bad and the WFS were making it drift. Koji aligned the beam into the PMC. I then restored the MC suspensions to where they were 8 days ago (back when the transmission and reflection were good). With the WFS OFF, this gave us a MC trans ~ 16000. With WFS ON it goes to 17500 which is about as good as its been over the last 80 days.

I centered the beam on the WFS with the MC unlocked and also centered the beam on the whole WFS path (it was near clipping between WFS 1 & 2). Also for some reason that beamsplitter which steers the beam onto WFS1 is a R=33% (!? why is this not a R=50% ??).

Steve, please swap this out to a BS1-1064-50-1025-45S if we have one sitting around. If not, we want to add this to the CVI purchase list, but not buy until we get a bigger list together.

I also centered this newly aligned beam into the IMC onto the PSL QPDs. We should now use these as a pointing reference for the beam into the IMC.

While doing this I noticed that the beam was almost clipping on the Uniblitz shutter used to block the PSL beam. That shutter is mounted too short and was also not centered horizontally. I removed it for now so that Steve can find a more adjustable mount for it and put it back into play. The beam going into the IMC is BIG, so you have to very careful when centering the shutter. Might be that we cannot leave it at 45 deg and still get a big enough aperture.

Note #3 for Steve: please also replace the mount for last steering mirror into the IMC with a Polanski or a Superman, that black Ultima is no good. Also the dogs must be steel - no aluminum dogs for our sensitive places.

Attachment 1: drifty.png
drifty.png
  9324   Thu Oct 31 21:22:00 2013 rana, kojiSummaryIOOmodulation beat note in MC servo

I hooked up the 4395 to the MC servo board test out (TP2A) and looked at the spectrum using our new SPAG4395.py script. We noticed a huge peak at ~3.8 MHz and correctly guessed that it was due to the beat between the MC modulation frequency 29.5 MHz and 3*f1 (~33 MHz).

So we tuned the Marconi for the main mod. from 11065910 to 11066099 Hz and saw the beat note disappear (to within the 1 Hz tuning precision of our Marconi).

New MC length tuning method! Alert the LA Times!

13031.png13031_200.png13031_200b.png

My conjecture is that this temperature dependent mismatch between the modulation frequency (f1) and the MC length  is what leads sometimes to our nasty saturating PC DRIVE signal. TBD.

  9325   Fri Nov 1 09:45:32 2013 SteveUpdateIOObeam dumps to be find

Quote:

Quote:

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 I couldn't find any dumps near the WFS. Koji looked. I looked twice. Maybe they are spooky and absorbing all of the light?

The MC alignment was bad and the WFS were making it drift. Koji aligned the beam into the PMC. I then restored the MC suspensions to where they were 8 days ago (back when the transmission and reflection were good). With the WFS OFF, this gave us a MC trans ~ 16000. With WFS ON it goes to 17500 which is about as good as its been over the last 80 days.

I centered the beam on the WFS with the MC unlocked and also centered the beam on the whole WFS path (it was near clipping between WFS 1 & 2). Also for some reason that beamsplitter which steers the beam onto WFS1 is a R=33% (!? why is this not a R=50% ??).

Steve, please swap this out to a BS1-1064-50-1025-45S if we have one sitting around. If not, we want to add this to the CVI purchase list, but not buy until we get a bigger list together.

I also centered this newly aligned beam into the IMC onto the PSL QPDs. We should now use these as a pointing reference for the beam into the IMC.

While doing this I noticed that the beam was almost clipping on the Uniblitz shutter used to block the PSL beam. That shutter is mounted too short and was also not centered horizontally. I removed it for now so that Steve can find a more adjustable mount for it and put it back into play. The beam going into the IMC is BIG, so you have to very careful when centering the shutter. Might be that we cannot leave it at 45 deg and still get a big enough aperture.

Note #3 for Steve: please also replace the mount for last steering mirror into the IMC with a Polanski or a Superman, that black Ultima is no good. Also the dogs must be steel - no aluminum dogs for our sensitive places.

No wonder they could not find the beam dumps. Last night was Haloween. They should of just said: Trick or treat! where are the beam dumps?

Attachment 1: razor_beam_dumps.jpg
razor_beam_dumps.jpg
  9334   Mon Nov 4 11:37:12 2013 SteveUpdateIOOPSL output shutter installed

 

 The PSL shutter is reinstalled.The base plate is delrin for isolation and the mount height is adjustable. The last steering mirror mount to be swapped in is ready. It is sitting on the top of the ITMX optical table cover with SS dogs.

There are two reflected spots on the north side of the Uniblitz shutter. They are coming from the vacuum window. They should be trapped also.

Attachment 1: Shutterisback.jpg
Shutterisback.jpg
  9336   Mon Nov 4 12:59:43 2013 JenneUpdateIOOMC alignment not so good after PSL output shutter installed

Quote:

  The PSL shutter is reinstalled.

 I'm not sure if Steve bumped something, or if it was just a fluke, but the MC didn't come back very nicely after Steve finished re-installing the shutter.

Earlier today, after Steve locked the PMC, MC trans looked good for over an hour (according to the striptool plot on the wall).  Then, the MC was unlocked for about an hour, presumably while Steve was working, he had the light blocked.  When he finished, the MC transmission was around 5,000 while usually it is around 17,000.  The reflection was around 3.4, rather than a best of below 0.5 (unlocked refl is 4.5).

Using Rana's ezcaservo trick to get the suspensions back to where they were at last good lock usually works (I used to do it by hand though).  However, today, it only got the reflection down to about 2.0.  So, I did the rest of the alignment by hand. 

After I did this, the reflection is down to 0.48.  Engaging the WFS makes the MC much more noisy, so I have them disabled currently. 

I have measured the spots, and if I compare them to the measurements that (I think it was Manasa) took last week, they look pretty bad. 

I think that we need to swap out the 2nd zigzag mirror, and then do a careful MC realignment.  It's certainly not worth doing the work, and then re-doing it after we swap out the zigzag mirror.

MCspots_4Nov2013.png

  9342   Tue Nov 5 00:39:43 2013 manasaUpdateIOOIFO alignment tuning

Information acknowledged from Steve:

The last steering mirror mount for IR on the PSL was swapped for a more robust one. Prior to swapping the ibeam positions on the PSL IOO QPDS in ang and pos were recorded.

What I did henceforth:

1. Once the last steering mirror was installed, I walked the beam to restore input pointing using the last 2 steering mirrors. It needed a lot of work in yaw as expected.

2. When the input pointing was recovered, MC locked right away in TEM00. I measured the MC spot positions and compared it with Jenne's measurement made prior to the swap. The spot positions were pretty close.

3. The input pointing was adjusted in pitch and yaw (on the last steering mirror) in small steps. MC alignment was recovered and spot positions were measured each time. After several iterations, the MC spot positions were pretty much centered. I recentered the WFS and reset the WFS offsets. MC is now locked with WFS enabled at ~16900 counts.

MC_spot.png

4. Since the arms were aligned this morning, I used the Y arm as reference and corrected for the input pointing using tip-tilts.

5. Arms locked right away. Note: ASS doesn't seem to be doing it's job. I had to manually align the arms for maximum on TRX and TRY.

6. MICH and PRMI lock were also recovered.

7. I started to check the status with ALS as well. But for reasons unknown, I don't see any ADC counts corresponding to the beat note. Looking at the beatbox there aren't any signs of disconnected cables.  I am saving this as a morning job to fix it.

  9343   Tue Nov 5 08:44:21 2013 SteveUpdateIOOafter last steering mirror mount swap

 The IOO Angle and IOO Position qpds  were recentered after this entry.

 Suggested corrections in elog entry #9323 are completed:

 1,  last steering mirror mount replaced by Polanski mount

 2,  PSL output shutter mount reconfigured

 IOO qpds are not centered. I failed to connect laptops to 40MARSian network.

Attachment 1: after_Shutter_SMm_installed.png
after_Shutter_SMm_installed.png
Attachment 2: afterlastSMmountswap.jpg
afterlastSMmountswap.jpg
  9352   Wed Nov 6 08:33:53 2013 SteveUpdateIOOPoiting changes of PSL

Quote:

 Full list tomorrow: IP-Ang & Pos, ETMY-T, ETMY-Oplev, ETMX-T, IOO-Ang & Pos

 RA: No one in the control room this evening can understand what this ELOG means. Please use more words.

 Yesterday the last steering mirror mount on the PSL was changed, Manasa recovered the MC alignment and Jenne locked the arms.

 I centered the following qpds:  ASC-IBQPD, LSC-TRY, SUS-ETMY_OPLEV, LSC-TRX, SUS_ETMX_OPLEV

 Touching the PSL pointing IOO-QPD_ANG & POS was a mistake. We lost the reference of the well refined MC input.

 

One and 20 days TRENDS  plot showing the PSL output drift in pitch can be power drop

However initial pointing is amazingly good. ( I wonder about the lens in front of the qpd ?)

Attachment 1: 1dayTRENDofPOITING.png
1dayTRENDofPOITING.png
Attachment 2: 20dayTRENDioo.png
20dayTRENDioo.png
  9358   Thu Nov 7 08:57:20 2013 SteveUpdateIOOPSL pointing monitoring

 The qpd sees the power drop as position change.

The laser  monitoring screen shows little changes of the Innolight 2W output. See elog 9292 to compare

So why does the PMC downgrade if the laser output is stationary ?

The PMC-T power is down to 0.75V  The auto locker does maximize power output.

It needs a manual alignment touch up.

 

 

Attachment 1: PMC11072013.jpg
PMC11072013.jpg
Attachment 2: PMCTqpdMon.png
PMCTqpdMon.png
  9365   Mon Nov 11 22:35:45 2013 RANAUpdateIOOPSL pointing monitoring

Since the pointing has gone bad again, I went to the PSL to investigate. Found some bad things and removed them:

1) There was a stopped down iris AGAIN in the main beam path, after the newly installed mirror mount. I opened it. Stop closing irises in the beam path.

2) The beam dump for the IOO QPD reflection was just some black aluminum. That is not a real dump. I removed it. We need two razor blade dumps for this.

3) There was an ND filter wheel (???) after one of the PMC steering mirrors. This is not good noise / optics practice. I removed it and dumped the beam in a real dump. No elog about this ?!#?

 

The attached trend shows the last 20 days. The big step ~2 weeks ago is when Steve replaced the steering mirror mount with the steel one. I don't understand the drift that comes after that.

 

Today I also spent ~1 hour repairing the Aldabella laptop. Whoever moved it from the PSL area to the SP table seems to have corrupted the disk by improper shutdown. Please stop shutting the lid and disconnecting it from the AC power unless you want to be fixing it. Its now running in some recovery mode. Lets leave it where it is next to the PSL and MC1.

I steered the MC suspensions back to where they were on the trends before the PSL mirror mount swap and then aligned the PSL beam into it by touching the last 2 steel mounts. Once the alignment was good without WFS, I centered the beams on the IOO QPDs. If it behaves good overnight, I will center the unlocked beams on the MC WFS.

 

Please stay off the PSL for a couple days if you can so that we can watch the drift. This means no opening the doors, turning on the lights, or heavy work around there.

Attachment 1: qpd.pdf
qpd.pdf
  9370   Tue Nov 12 23:48:23 2013 RANAUpdateIOOPSL pointing monitoring

Since I saw that the trend was good, I aligned the MC refl path to the existing IMC alignment:

  1. removed a broken IRIS that was clipping the reflected beam (and its mount)
  2. moved the first 1" diameter steering mirror on the high power path after the 2" diameter R=10% steering mirror. It was not centered.
  3. Moved the lens just upstream of the LSC RFPD away from the PD by ~5 mm. The beam going towards the WFS was too close to this mount and I could see some glow.
  4. Centered the beam on all optics in the WFS path and then the WFS DC.
  5. Centered beam on LSC RFPD.

The reflected spots from the PD are not hitting the dump correctly. WE need to machine a shorter post to lower the dump by ~1 cm to catch the beams.

  9389   Fri Nov 15 09:24:41 2013 SteveUpdateIOOWFS with beam dumps

This is a proposal to move WFSs such way that their reflected beam can be trapped.

Later ps: Nic will take care of the Gouy phase telescopes.

Attachment 1: MCwfsRefTraped.jpg
MCwfsRefTraped.jpg
  9390   Fri Nov 15 09:27:58 2013 KojiUpdateIOOWFS with beam dumps

Unfortunately this does not work. These WFSs are not the detectors which we can move freely.
In order to move the WFS detectors, we need the precise design of the Gouy phase for each WFS heads.
Without the design, we can't move the detectors.

  9421   Thu Nov 21 16:32:20 2013 SteveUpdateIOOPMC needs a touch of love

 

 The PMC power degrading on this 3 days plot. MC2 -T = 14,200 counts. C1:IOO-MC_TRANS_SUM can not be ploted in dataviewer. The MEDM screen has a valid number.

Initial pointing is not so bad (what does "not so bad" mean ???)

C1iscey comes and goes again.

 

Attachment 1: PMCplus.png
PMCplus.png
  9431   Sat Nov 30 23:50:28 2013 ranaUpdateIOOmode cleaner not locking

Quote:

 I used our procedure from this entry to set the IMC board offset as well as the FSS board offset.

I found this afternoon that the MC was having trouble locking: the PC path was railing as soon as the boost was engaged. Could be that there's some misalignment on the PSL which has led to some RAM having to be canceled by this new offset. Let's see if its stable for awhile.

 I felt in my bones that the MC was in trouble so I came by and noticed that it hadn't locked for a couple hours. The FSS SLOW was at -1.6V, but putting it back to zero didn't fix things. I adjusted the FSS error point offset to +1 and that took the FSS_FAST off of the +10 V rail. Relocked and seems OK.

We need to plan to make the M Evans mod to the FSS box to make the PC drive less angry.

Last 40 days of MC Alignment trends  show that the recent MC WFS tuning / offseting worked out OK. MC REFL seems low and flat.

Attachment 1: mcdrift.png
mcdrift.png
  9448   Fri Dec 6 15:57:41 2013 SteveUpdateIOObeam dumps for PSL pointing monitoring

Quote:

Since the pointing has gone bad again, I went to the PSL to investigate. Found some bad things and removed them:

1) There was a stopped down iris AGAIN in the main beam path, after the newly installed mirror mount. I opened it. Stop closing irises in the beam path.

2) The beam dump for the IOO QPD reflection was just some black aluminum. That is not a real dump. I removed it. We need two razor blade dumps for this.

3) There was an ND filter wheel (???) after one of the PMC steering mirrors. This is not good noise / optics practice. I removed it and dumped the beam in a real dump. No elog about this ?!#?

 

The attached trend shows the last 20 days. The big step ~2 weeks ago is when Steve replaced the steering mirror mount with the steel one. I don't understand the drift that comes after that.

 

Today I also spent ~1 hour repairing the Aldabella laptop. Whoever moved it from the PSL area to the SP table seems to have corrupted the disk by improper shutdown. Please stop shutting the lid and disconnecting it from the AC power unless you want to be fixing it. Its now running in some recovery mode. Lets leave it where it is next to the PSL and MC1.

I steered the MC suspensions back to where they were on the trends before the PSL mirror mount swap and then aligned the PSL beam into it by touching the last 2 steel mounts. Once the alignment was good without WFS, I centered the beams on the IOO QPDs. If it behaves good overnight, I will center the unlocked beams on the MC WFS.

 

Please stay off the PSL for a couple days if you can so that we can watch the drift. This means no opening the doors, turning on the lights, or heavy work around there.

 IOO pointing monitoring qpds received razor beam dumps on their refs.

The Pos QPD was rotated and recentered.

The Ang QPD was left untouched.

TREND plot of 23 days is attached.

Attachment 1: IOO_QPD_MONS.jpg
IOO_QPD_MONS.jpg
Attachment 2: PointingTrend23d.png
PointingTrend23d.png
  9452   Tue Dec 10 10:07:01 2013 SteveUpdateIOOmore beam traps

 New razor beam dump installed to trap reflected beam of the input vacuum window.

 

Attachment 1: InputWindowRefDump.jpg
InputWindowRefDump.jpg
Attachment 2: InpWindowRefDupm.jpg
InpWindowRefDupm.jpg
  9453   Tue Dec 10 15:13:55 2013 KojiUpdateIOOIMC servo inspection

Yesterday evening I inspected at IMC servo as a preparation of the CM servo recommissioning.

More details to come.

  9457   Thu Dec 12 14:57:01 2013 KojiUpdateIOOIMC servo inspection

In order to accomplish CARM control with the PSL laser frequency, we use two actuators.

One is the longitudinal direction of one of the MC mirrors. The londitudinal motion of the MC induces
the laser frequency control via the MC servo. As we move the mirror, the range is sort of big,
but the BW is limited by the mechanical response.

The other is the additive offset path. We inject a signal to the additional input port of the MC.
The MC servo supresses this injection by giving the same amount but oppsite sign offset to
the error signal (before the addtion of the inputs). The bandwidth of this AO path is limited
by the bandwidth of the MC servo. Basically the BW of the AO path is about 1/10 of that of the MC servo.

In order to confirm the capability of the AO path as a frequency actuator, 1) OLTF of the MC servo
2) TF of the AO input to the servo error was measured.

Attachment 1 shows the openloop TF of the MC servo. The UGF seems just little bit higher than
100kHz. The OLTF is empirically modelled by LISO as seen in the figure.

Attachment 2 shows the TF from the additive input (In2) to the error monitor (MC Servo module Q error mon).
The gain setting of the MC servo box was: In1 +18dB, In2 0dB. The measured TF has arbitorary gain 
due to the gain setting, the measuemrent data was multiplied by 4 to mach the DC value to the unity.
This is to compare the measurement with the prediction from the OLTF.

The AO path TF is expected to show the character of -G/(1+G) where G is the OLTF. In my case,
G = 0.75*OLTF showed the best maching. There might have been some misalignment of the MC
upon the AO path measurement as I found after the measurement.

From the plot , we can see that the response is flat up to 20kHz. Above that it rapidly raises.
This should be dealt with the CM servo filter as the bump may hit the unity gain. Since we have to use
strong roll off to avoid the bump, this will eat the phase margin at low frequency.

In the case that we don't like this bump:
This bump is caused by low phase mergin of the OLTF at 30~40kHz. If the total gain
is increased, the bump is reduced. Or, we can decrease the PZT loop gain in order to
reduce the dip at the crossover ferquency between the PZT and PC loops. In both cases,
the PC path suffers more actuation. We may need to think about the HV actuation option
for the PC (Apex PA85).

Well, let's see how the CM servo can handle this.
The key point here is that we have enough data to start the design of the CM servo.

Attachment 1: OLTF_IMC.pdf
OLTF_IMC.pdf
Attachment 2: AOTF_IMC.pdf
AOTF_IMC.pdf
Attachment 3: 131209.zip
  9468   Fri Dec 13 18:03:00 2013 DenUpdateIOOcommon mode servo

Quote:

Well, let's see how the CM servo can handle this.
The key point here is that we have enough data to start the design of the CM servo.

 It seems to me that current design of the common mode servo is already fine. Attached plots show common mode open and closed loop transfer function.

Frequency response of the servo is taken from the document D040180. I assumed coupled cavity pole to be ~100 Hz.

The only question is if our EOM has enough range. Boost 2 increases noise injection by 10 dB in the frequency range 20-50 kHz. Boost 3 has even higher factor.

Attachment 1: CM_OL.pdf
CM_OL.pdf
Attachment 2: CM_CL.pdf
CM_CL.pdf
  9470   Fri Dec 13 23:07:04 2013 KojiUpdateIOOcommon mode servo

Looks good.

Once the control cable (bakplane cable) is identified, we can install the module to the LSC analog rack.

We should be able to test the CM servo with either POX or POY and only one correspoding arm without modifying the servo TF.
Just for this test, we don't need to use MCL.

  9473   Sat Dec 14 13:46:54 2013 DenUpdateIOOlow bandwidth MCL loop

Last time we designed MCL loop with UGF ~ 30 Hz and I think, it was hard to lock the arm because of large frequency noise injected to IFO.

This time I made a low bandwidth MCL loop with UGF=8 Hz. MCL error RMS is suppressed by factor of 10 and arms lock fine.

Attached plots show MCL OL, MCL error suppression and frequency noise injection to arms.

It is interesting that spectrum of arms increases below 1 Hz meaning that IMC sensing noise dominates in this range.

I did not include the loop into the IMC autolocker. I think it is necessary to turn it on only during day time activity and when beatnote is moving too much during arm stabilization.

Attachment 1: MCL_OL.pdf
MCL_OL.pdf
Attachment 2: MCL_ERR.pdf
MCL_ERR.pdf
Attachment 3: MCL_ARMS.pdf
MCL_ARMS.pdf
Attachment 4: MCL_MEDM.png
MCL_MEDM.png
  9521   Mon Jan 6 18:32:17 2014 RANAUpdateIOOMC1/3 kicked this morning at 8:30

 The trend shows a big jolt to the MC1/3 pointing this morning at 8:30.

Was anyone working anywhere near there today? There is no elog.

If not, we will have to put a 'no janitor' sign on all of the 40m doors permanently to prevent mops misaligning our interferometer.

Attachment 1: kicked.png
kicked.png
  9522   Mon Jan 6 20:52:09 2014 JenneUpdateIOOMC1/3 kicked this morning at 8:30

When I got in this morning at 9-something (9:45 maybe?), Steve was taking dust photos on the AS table, of the MC Refl path.  Other than that, I don't have any information. 

Also, Tuesday is our traditional janitor day, so I'm hesitant to put our blame there.  (I think we've kept Tuesdays, even though we're on a less-often schedule....Steve will have to correct me if I'm wrong on this).

  9524   Tue Jan 7 10:44:13 2014 SteveUpdateIOOMC drift

Quote:

 The trend shows a big jolt to the MC1/3 pointing this morning at 8:30.

Was anyone working anywhere near there today? There is no elog.

If not, we will have to put a 'no janitor' sign on all of the 40m doors permanently to prevent mops misaligning our interferometer.

 I was taking pictures at the AP table at the morning and ETMX optical table after noon. There was no activity on the IOO chamber.

 Look at the last 2 hours of  Rana's trend plot. MC1 and MC2 sensor voltage started increasing.

I think it was a drift action.

Attachment 1: 2dTrend.png
2dTrend.png
Attachment 2: driftNotKick.png
driftNotKick.png
  9525   Tue Jan 7 11:11:36 2014 ranaUpdateIOOMC drift

 

 NOT drift. The sudden steps are certainly the result of being kicked. The slow drift at the end of the day might be a slow strain relaxation.

It pays to be careful and not put too much weight or impulsive forces on the chambers or tables.

  9526   Tue Jan 7 16:41:08 2014 manasaUpdateIOOWFS moving MC suspensions

Quote:

 The trend shows a big jolt to the MC1/3 pointing this morning at 8:30.

Was anyone working anywhere near there today? There is no elog.

If not, we will have to put a 'no janitor' sign on all of the 40m doors permanently to prevent mops misaligning our interferometer.

The MC trend for the last 2 days shows that the MC suspensions were kicked again earlier today.  Looking back at the suspension channel INMONs along with the MC trans sum shows that the suspensions get kicked everytime MC locks and unlocks. (Attch:1)

So I checked the effect of WFS on the suspensions by disabling and enabling the WFS feedback servo (Attch:2).

Since the IMC is not at it best pointing, whenever the  MC autolocker runs and enables the WFS, the suspensions look like they are getting kicked.  But really, it's just the WFS doing their job. 

Edit, JCD:  What this really means is that our DC MC pointing is bad, and we need to move the MC suspensions to offload the WFS.  (All of the WFS output numbers for MC1 and 3 were around 100, which is pretty big for those numbers).  We should resurrect the WFS offloading scripts so that we can do this more regularly, and not have to do it by hand.

Attachment 1: 2dayMCtrend.png
2dayMCtrend.png
Attachment 2: WFSvsMCsuspensions.png
WFSvsMCsuspensions.png
  9527   Tue Jan 7 17:16:04 2014 manasaUpdateIOOMC aligned

Quote:

Edit, JCD:  What this really means is that our DC MC pointing is bad, and we need to move the MC suspensions to offload the WFS.  (All of the WFS output numbers for MC1 and 3 were around 100, which is pretty big for those numbers).  We should resurrect the WFS offloading scripts so that we can do this more regularly, and not have to do it by hand.

 Aligned MC to offload the WFS

1. Turned OFF the WFS feedback servo.

2. Aligned the MC suspensions by moving the pit and yaw sliders. MC trans sum brought from ~11000 counts to ~15000 counts. MC RFPD DCMON reads 0.45 counts.

3. Turned ON the WFS servo. The WFS output now reads in the order of 0 to +/-15.

4. Measured the MC spot positions. The spot positions look like they moved for the better compared to what they were yesterday.

 

Attachment 1: MCspots.png
MCspots.png
  9528   Tue Jan 7 20:57:41 2014 JenneUpdateIOOMC aligned

[Rana, Jenne]

We turned off the WFS servos, and looked at the MC REFL DC, and saw that it was still good, so we said that since the MC spots are pretty good, that we'll keep this alignment for now. 

Rana put the beam back on the center of the IOO QPDs on the PSL table.

We switched a steering mirror in the WFS path that was the wrong handed-ness to be the correct handed-ness, then put the beam on the centers of the WFS.  We turned on the WFS, and everything seems good.

While we were out on the table, we also changed the anodized aluminum dump for a razor dump, to catch the reflection from the 2inch lens that is the first thing the MC refl path sees out of vac.

There were no major drifts in the WFS error signals while we were gone for dinner, so the MC seems okay for now.

  9529   Tue Jan 7 21:00:02 2014 JenneUpdateIOOIP POS, IP ANG aligned

After locking the arms (after the MC alignment work), Manasa and I aligned IP POS, IP ANG, and both end transmission QPDs. 

We noticed that IP ANG is clipping in yaw as it comes onto the end table.  It looks to me like it's clipping on the edge of the plastic box's aperture, but I can't guarantee that it's not also clipping elsewhere. 

  9532   Tue Jan 7 23:09:10 2014 manasaUpdateIOOMC aligned

Quote:

[Rana, Jenne]

We turned off the WFS servos, and looked at the MC REFL DC, and saw that it was still good, so we said that since the MC spots are pretty good, that we'll keep this alignment for now. 

Rana put the beam back on the center of the IOO QPDs on the PSL table.

We switched a steering mirror in the WFS path that was the wrong handed-ness to be the correct handed-ness, then put the beam on the centers of the WFS.  We turned on the WFS, and everything seems good. 

There were no major drifts in the WFS error signals while we were gone for dinner, so the MC seems okay for now.

 The last 4 hour trend for WFS error signals show some amount of drift. We should still look at the long term trend to solve the issue.

Attachment 1: WFSdrift.png
WFSdrift.png
  9577   Mon Jan 27 12:26:00 2014 KojiUpdateIOOIOO Slow Actuator Servo threshold changed

In order to activate the slow actuator servo for the MC locking,
the threshold level for this servo (C1:PSL-FSS_LOCKEDLEVEL) was changed from 10000 to 700.

Now the servo started to move the PZT fast out to be controlled to 5V.

  9580   Tue Jan 28 09:51:47 2014 SteveUpdateIOOlow power pointing

 

PSL output is stable.

Attachment 1: IOO4dlowpr.png
IOO4dlowpr.png
  9632   Thu Feb 13 13:18:33 2014 manasaUpdateIOOMC needed some help

The MC has been funny since yesterday. I checked the suspensions INMON channels and they seemed ok. So I went ahead and tweaked the alignment with WFS disabled (yesterday). Although the WFS PDs were cenetered at this point, the WFS servo was throwing the MC in a not-so-happy state. We worked with the WFS servo OFF all of yesterday.

This morning,

* I fine tuned the MC alignment from yesterday (TRANS_SUM > 17800 counts)

* measured the spot positions

* recentered the spots on the WFS PDs (was already quite centered)

*reset the WFS filterbank offsets.

The MC has been locked happily since then with autolocker and WFS servo enabled.

  9645   Tue Feb 18 14:28:15 2014 JenneUpdateIOOMC unstable - centering spots helped

As we've been seeing a bit lately, the MC will be locked happily for several hours, but then it will start misbehaving. 

Today, I measured the spots on the MC mirrors, and found that the MC2 spot was quite far off in yaw (about -3.5 cm).  I recentered the MC2 spot, and then (with the MCWFS on), moved MC1 and 3 until their WFS outputs were close to zero (they had gone up to 100+).  In the ~15 minutes since doing that, the MC refl signal is not oscillating like it was, the transmission is up, and the MC has not unlocked. 

To reiterate, I did not touch any settings of anything, except the alignment of the MC mirrors to center the MC2 spot, and then offload the WFS.  Next time the MC starts acting up, we should measure the spots, and roughly center them, before messing with any other settings.  Note however, that this is a ~10 minute procedure (including the fact that one spot measurement takes a little less than 5 minutes).  This need not be a several hour endeavour. 

  9677   Wed Feb 26 02:20:35 2014 JenneUpdateIOOMC unhappy

I've asked Manasa and Q to have a look at the MC in the morning.  Rana and I have found it to be slightly uncooperative in relocking after a lockloss.

The concern is that we may be (by actuating on things during lock, or during a lockloss) ringing up some mode, maybe a violin mode in one of the suspensions, maybe a PZT mode of some sort.  If we are, and then we have to push with the PZT on the laser to lock things, that may be why the laser's PZT RMS (on the FSS screen) is so often above 1Vrms.  When we close the PSL shutter, the rms is low, like 0.6 or something, and it stays flat.  As we've all see many a' time, the red trace on the top projector plot is pretty erratic throughout the day when the MC is locked or trying to lock.

We have found that just letting the autolocker go doesn't seem to work very well, and sometimes the MC just doesn't want to re-lock.  Closing the PSL shutter or disabling the autolocker for a few minutes (5ish) doesn't do anything, but leaving it closed for a long time (30 ish minutes) helps a lot.  The MC  will relock immediately after a nice long break. 

 

  9678   Wed Feb 26 10:08:14 2014 SteveUpdateIOOIOO trend

 

 The MC is happy (but only for this tiny snapshot in time and most probably will go dysfunctional again as it has been for several months, as of this writing)

Attachment 1: IOOtrend3&24h.png
IOOtrend3&24h.png
  9695   Wed Mar 5 19:27:24 2014 manasaUpdateIOOMC calmed down

The IMC has not been behaving well since this morning and totally not happy when Q was finishing his measurements. The WFS servo had large offsets in pitch. Looking back at the trend and using ezcaservo to restore the suspensions did not help.

I realigned the IMC and brought TRANS SUM to ~18000 and MCREFL to < 0.5. The spot positions are not very good; nearly 2 mm off in pitch on MC1 and MC3. But after the alignment of MC, the WFS servo offsets were below +/-20.

The MC has been locked stably with WFS servo ON for the last few hours.

P.S. I did not touch the WFS pointing or reset the WFS offsets.

  9697   Thu Mar 6 09:47:11 2014 SteveUpdateIOOMC trend of 20 days

Quote:

The IMC has not been behaving well since this morning and totally not happy when Q was finishing his measurements. The WFS servo had large offsets in pitch. Looking back at the trend and using ezcaservo to restore the suspensions did not help.

I realigned the IMC and brought TRANS SUM to ~18000 and MCREFL to < 0.5. The spot positions are not very good; nearly 2 mm off in pitch on MC1 and MC3. But after the alignment of MC, the WFS servo offsets were below +/-20.

The MC has been locked stably with WFS servo ON for the last few hours.

P.S. I did not touch the WFS pointing or reset the WFS offsets.

 

Attachment 1: IOO_20days.png
IOO_20days.png
  9701   Thu Mar 6 19:17:05 2014 manasaUpdateIOOMC calmed down

Quote:

The IMC has not been behaving well since this morning and totally not happy when Q was finishing his measurements. The WFS servo had large offsets in pitch. Looking back at the trend and using ezcaservo to restore the suspensions did not help.

I realigned the IMC and brought TRANS SUM to ~18000 and MCREFL to < 0.5. The spot positions are not very good; nearly 2 mm off in pitch on MC1 and MC3. But after the alignment of MC, the WFS servo offsets were below +/-20.

The MC has been locked stably with WFS servo ON for the last few hours.

P.S. I did not touch the WFS pointing or reset the WFS offsets.

MC remained locked with WFS enabled all through last night and this morning. Koji dropped by and looked at the MC. The MC WFS servo, though stable, was at the edge of becoming unstable. This was because I did not touch the WFS pointing on the QPDs yesterday after realigning. So I recentered the WFS, reset the WFS filterbank offsets and reenabled the servo.

I measured the spot positions on MC mirrors for reference.

Spot positions in mm (MC1,2,3 pit MC1,2,3 yaw): [1.405767579680834, 0.79369009503571208, 1.3220430681427462, -1.2937873599406551, -1.1704264340968924, -1.2518046122798692]

Attachment 1: MC_spots_Mar6.png
MC_spots_Mar6.png
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